For aluminum alloys in general, the thermal conductivity increases as the aluminum content of the alloy gets higher. Therefore, in cases where a high thermal conductivity is necessary, the use of pure aluminum may be considered, but pure aluminum has the problems of low strength and low castability, so it was not possible to cast things having complex shapes and thin-walled portions.
Accordingly, in cases where heatsinks having a complex shape were manufactured, for example, as described in Japanese Unexamined Patent Publication No. 2001-316748, Japanese Unexamined Patent Publication No. 2002-3972, and Japanese Unexamined Patent Publication No. 2002-105571, aluminum alloys with silicon added were used in order to improve castability, even at the expense of a certain degree of thermal conductivity.
However, along with the increase in performance of electronic devices in recent years, heatsinks with higher performance have come to be sought. Accordingly, the development of alloys having better thermal conductivity than conventional aluminum alloy castings has been awaited.